!--------------------------------------------------------------------------------------------------!
!   CP2K: A general program to perform molecular dynamics simulations                              !
!   Copyright 2000-2024 CP2K developers group <https://cp2k.org>                                   !
!                                                                                                  !
!   SPDX-License-Identifier: GPL-2.0-or-later                                                      !
!--------------------------------------------------------------------------------------------------!

! **************************************************************************************************
!> \brief function that build the dft section of the input
!> \par History
!>      01.2013 moved out of input_cp2k_dft [MI]
!> \author MI
! **************************************************************************************************
MODULE input_cp2k_properties_dft
   USE bibliography, ONLY: Futera2017, &
                           Iannuzzi2005, &
                           Kondov2007, &
                           Luber2014, &
                           Putrino2000, &
                           Putrino2002, &
                           Sebastiani2001, &
                           Weber2009
   USE cp_output_handling, ONLY: add_last_numeric, &
                                 cp_print_key_section_create, &
                                 debug_print_level, &
                                 high_print_level, &
                                 low_print_level, &
                                 medium_print_level, &
                                 silent_print_level
   USE cp_units, ONLY: cp_unit_to_cp2k
   USE input_constants, ONLY: &
      current_gauge_atom, current_gauge_r, current_gauge_r_and_step_func, &
      current_orb_center_atom, current_orb_center_box, current_orb_center_common, &
      current_orb_center_wannier, do_et_ddapc, do_full_density, do_no_et, do_spin_density, &
      gto_cartesian, gto_spherical, int_ldos_none, int_ldos_x, int_ldos_y, int_ldos_z, oe_gllb, &
      oe_lb, oe_none, oe_saop, oe_shift, ot_precond_full_all, ot_precond_full_kinetic, &
      ot_precond_full_single, ot_precond_full_single_inverse, ot_precond_none, &
      ot_precond_s_inverse, scan_x, scan_xy, scan_xyz, scan_xz, scan_y, scan_yz, scan_z, &
      tddfpt_dipole_berry, tddfpt_dipole_length, tddfpt_dipole_velocity, tddfpt_kernel_full, &
      tddfpt_kernel_none, tddfpt_kernel_stda, use_mom_ref_coac, use_mom_ref_com, &
      use_mom_ref_user, use_mom_ref_zero
   USE input_cp2k_atprop, ONLY: create_atprop_section
   USE input_cp2k_dft, ONLY: create_ddapc_restraint_section, &
                             create_interp_section, &
                             create_lrigpw_section, &
                             create_mgrid_section
   USE input_cp2k_kpoints, ONLY: create_kpoint_set_section
   USE input_cp2k_loc, ONLY: create_localize_section
   USE input_cp2k_resp, ONLY: create_resp_section
   USE input_cp2k_xc, ONLY: create_xc_section
   USE input_keyword_types, ONLY: keyword_create, &
                                  keyword_release, &
                                  keyword_type
   USE input_section_types, ONLY: section_add_keyword, &
                                  section_add_subsection, &
                                  section_create, &
                                  section_release, &
                                  section_type
   USE input_val_types, ONLY: char_t, &
                              integer_t, &
                              lchar_t, &
                              logical_t, &
                              real_t
   USE kinds, ONLY: dp
   USE string_utilities, ONLY: s2a
#include "./base/base_uses.f90"

   IMPLICIT NONE
   PRIVATE

   LOGICAL, PRIVATE, PARAMETER :: debug_this_module = .TRUE.
   CHARACTER(len=*), PARAMETER, PRIVATE :: moduleN = 'input_cp2k_properties_dft'

   PUBLIC :: create_properties_section

CONTAINS

! **************************************************************************************************
!> \brief Create the PROPERTIES section
!> \param section the section to create
!> \author teo
! **************************************************************************************************
   SUBROUTINE create_properties_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: subsection

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="PROPERTIES", &
                          description="This section is used to set up the PROPERTIES calculation.", &
                          n_keywords=0, n_subsections=6, repeats=.FALSE.)

      NULLIFY (subsection, keyword)

      CALL create_linres_section(subsection, create_subsections=.TRUE.)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_et_coupling_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_resp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_atprop_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL cp_print_key_section_create(subsection, __LOCATION__, name="FIT_CHARGE", &
                                       description="This section is used to print the density derived atomic point charges. "// &
                                       "The fit of the charges is controlled through the DENSITY_FITTING section", &
                                       print_level=high_print_level, filename="__STD_OUT__")
      CALL keyword_create(keyword, __LOCATION__, name="TYPE_OF_DENSITY", &
                          description="Specifies the type of density used for the fitting", &
                          usage="TYPE_OF_DENSITY (FULL|SPIN)", &
                          enum_c_vals=s2a("FULL", "SPIN"), &
                          enum_i_vals=(/do_full_density, do_spin_density/), &
                          enum_desc=s2a("Full density", "Spin density"), &
                          default_i_val=do_full_density)
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_tddfpt2_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_bandstructure_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_tipscan_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_properties_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      a linear response calculation
!>      Available properties : none
!> \param section the section to create
!> \param create_subsections indicates whether or not subsections should be created
!> \param default_set_tdlr default parameters to be used if called from TDDFPT
!> \author MI
! **************************************************************************************************
   SUBROUTINE create_linres_section(section, create_subsections, default_set_tdlr)
      TYPE(section_type), POINTER                        :: section
      LOGICAL, INTENT(in)                                :: create_subsections
      LOGICAL, INTENT(IN), OPTIONAL                      :: default_set_tdlr

      INTEGER                                            :: def_max_iter, def_precond
      REAL(KIND=DP)                                      :: def_egap, def_eps, def_eps_filter
      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key)

      IF (PRESENT(default_set_tdlr)) THEN
         def_egap = 0.02_dp
         def_eps = 1.0e-10_dp
         def_eps_filter = 1.0e-15_dp
         def_max_iter = 100
         def_precond = ot_precond_full_single_inverse
      ELSE
         def_egap = 0.2_dp
         def_eps = 1.e-6_dp
         def_eps_filter = 0.0_dp
         def_max_iter = 50
         def_precond = ot_precond_none
      END IF

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="linres", &
                          description="The linear response is used to calculate one of the "// &
                          "following properties: nmr, epr, raman, ... ", &
                          n_keywords=5, n_subsections=2, repeats=.FALSE., &
                          citations=(/Putrino2000/))

      CALL keyword_create(keyword, __LOCATION__, name="EPS", &
                          description="target accuracy for the convergence of the conjugate gradient.", &
                          usage="EPS 1.e-6", default_r_val=def_eps)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="EPS_FILTER", &
                          description="Filter threshold for response density matrix.", &
                          usage="EPS 1.e-8", default_r_val=def_eps_filter)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MAX_ITER", &
                          description="Maximum number of conjugate gradient iteration to be performed for one optimization.", &
                          usage="MAX_ITER 200", default_i_val=def_max_iter)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART_EVERY", &
                          description="Restart the conjugate gradient after the specified number of iterations.", &
                          usage="RESTART_EVERY 200", default_i_val=50)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create( &
         keyword, __LOCATION__, name="PRECONDITIONER", &
         description="Type of preconditioner to be used with all minimization schemes. "// &
         "They differ in effectiveness, cost of construction, cost of application. "// &
         "Properly preconditioned minimization can be orders of magnitude faster than doing nothing.", &
         usage="PRECONDITIONER FULL_ALL", &
         default_i_val=def_precond, &
         enum_c_vals=s2a("FULL_ALL", "FULL_SINGLE_INVERSE", "FULL_SINGLE", "FULL_KINETIC", "FULL_S_INVERSE", &
                         "NONE"), &
         enum_desc=s2a("Most effective state selective preconditioner based on diagonalization, "// &
                       "requires the ENERGY_GAP parameter to be an underestimate of the HOMO-LUMO gap. "// &
                       "This preconditioner is recommended for almost all systems, except very large systems where "// &
                       "make_preconditioner would dominate the total computational cost.", &
                       "Based on H-eS cholesky inversion, similar to FULL_SINGLE in preconditioning efficiency "// &
                       "but cheaper to construct, "// &
                       "might be somewhat less robust. Recommended for large systems.", &
                       "Based on H-eS diagonalisation, not as good as FULL_ALL, but somewhat cheaper to apply. ", &
                       "Cholesky inversion of S and T, fast construction, robust, and relatively good, "// &
                       "use for very large systems.", &
                       "Cholesky inversion of S, not as good as FULL_KINETIC, yet equally expensive.", &
                       "skip preconditioning"), &
         enum_i_vals=(/ot_precond_full_all, ot_precond_full_single_inverse, ot_precond_full_single, &
                       ot_precond_full_kinetic, ot_precond_s_inverse, ot_precond_none/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ENERGY_GAP", &
                          description="Energy gap estimate [a.u.] for preconditioning", &
                          usage="ENERGY_GAP 0.1", &
                          default_r_val=def_egap)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART", &
                          description="Restart the response calculation if the restart file exists", &
                          usage="RESTART", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="WFN_RESTART_FILE_NAME", &
                          variants=(/"RESTART_FILE_NAME"/), &
                          description="Root of the file names where to read the response functions from "// &
                          "which to restart the calculation of the linear response", &
                          usage="WFN_RESTART_FILE_NAME <FILENAME>", &
                          type_of_var=lchar_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      IF (create_subsections) THEN
         NULLIFY (subsection)

         CALL create_localize_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_current_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_nmr_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_spin_spin_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_epr_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_polarizability_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_dcdr_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL create_vcd_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         CALL section_create(subsection, __LOCATION__, name="PRINT", &
                             description="printing of information during the linear response calculation", &
                             repeats=.FALSE.)

         CALL cp_print_key_section_create( &
            print_key, __LOCATION__, "program_run_info", &
            description="Controls the printing of basic iteration information during the LINRES calculation", &
            print_level=low_print_level, add_last=add_last_numeric, filename="__STD_OUT__")
         CALL section_add_subsection(subsection, print_key)
         CALL section_release(print_key)

         CALL cp_print_key_section_create(print_key, __LOCATION__, "RESTART", &
                                          description="Controls the dumping of restart file of the response wavefunction. "// &
                                          "For each set of response functions, i.e. for each perturbation, "// &
                                          "one different restart file is dumped. These restart files should be "// &
                                          "employed only to restart the same type of LINRES calculation, "// &
                                          "i.e. with the same perturbation.", &
                                          print_level=low_print_level, common_iter_levels=3, each_iter_names=s2a("ITER"), &
                                          add_last=add_last_numeric, each_iter_values=(/3/), filename="")
         CALL section_add_subsection(subsection, print_key)
         CALL section_release(print_key)

         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

      END IF

   END SUBROUTINE create_linres_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      calculation of position perturbation  DFPT
!> \param section ...
!> \author Sandra Luber, Edward Ditler
! **************************************************************************************************
   SUBROUTINE create_dcdr_section(section)

      TYPE(section_type), POINTER                        :: section

      LOGICAL                                            :: failure
      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      failure = .FALSE.
      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))

      IF (.NOT. failure) THEN
         CALL section_create(section, __LOCATION__, name="DCDR", &
                             description="Compute analytical gradients the dipole moments.", &
                             n_keywords=50, n_subsections=1, repeats=.FALSE.)

         CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                             description="controls the activation of the APT calculation", &
                             usage="&DCDR T", &
                             default_l_val=.FALSE., &
                             lone_keyword_l_val=.TRUE.)
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         CALL keyword_create(keyword, __LOCATION__, name="LIST_OF_ATOMS", &
                             description="Specifies a list of atoms.", &
                             usage="LIST {integer} {integer} .. {integer}", repeats=.TRUE., &
                             n_var=-1, type_of_var=integer_t)
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         CALL keyword_create(keyword, __LOCATION__, name="DISTRIBUTED_ORIGIN", &
                             variants=(/"DO_GAUGE"/), &
                             description="Use the distributed origin (DO) gauge?", &
                             usage="DISTRIBUTED_ORIGIN T", &
                             default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         CALL keyword_create(keyword, __LOCATION__, name="ORBITAL_CENTER", &
                             description="The orbital center.", &
                             usage="ORBITAL_CENTER WANNIER", &
                             default_i_val=current_orb_center_wannier, &
                             enum_c_vals=s2a("WANNIER", "COMMON", "ATOM", "BOX"), &
                             enum_desc=s2a("Use the Wannier centers.", &
                                           "Use a common center (works only for an isolate molecule).", &
                                           "Use the atoms as center.", &
                                           "Boxing."), &
                             enum_i_vals=(/current_orb_center_wannier, current_orb_center_common, &
                                           current_orb_center_atom, current_orb_center_box/))
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         CALL keyword_create(keyword, __LOCATION__, name="REFERENCE", &
                             description="Gauge origin of the velocity gauge factor.", &
                             enum_c_vals=s2a("COM", "COAC", "USER_DEFINED", "ZERO"), &
                             enum_desc=s2a("Use Center of Mass", &
                                           "Use Center of Atomic Charges", &
                                           "Use User-defined Point", &
                                           "Use Origin of Coordinate System"), &
                             enum_i_vals=(/use_mom_ref_com, &
                                           use_mom_ref_coac, &
                                           use_mom_ref_user, &
                                           use_mom_ref_zero/), &
                             default_i_val=use_mom_ref_zero)
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         CALL keyword_create(keyword, __LOCATION__, name="REFERENCE_POINT", &
                             description="User-defined reference point of the velocity gauge factor.", &
                             usage="REFERENCE_POINT x y z", &
                             repeats=.FALSE., n_var=3, type_of_var=real_t, unit_str='bohr')
         CALL section_add_keyword(section, keyword)
         CALL keyword_release(keyword)

         NULLIFY (subsection)
         CALL section_create(subsection, __LOCATION__, name="PRINT", &
                             description="print results of the magnetic dipole moment calculation", &
                             repeats=.FALSE.)

         CALL cp_print_key_section_create(print_key, __LOCATION__, "APT", &
                                          description="Controls the printing of the electric dipole gradient", &
                                          print_level=low_print_level, add_last=add_last_numeric, filename="")
         CALL section_add_subsection(subsection, print_key)
         CALL section_release(print_key)

         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

         NULLIFY (subsection)
         CALL create_interp_section(subsection)
         CALL section_add_subsection(section, subsection)
         CALL section_release(subsection)

      END IF

   END SUBROUTINE create_dcdr_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      calculation of VCD spectra using DFPT
!> \param section ...
!> \author Sandra Luber, Tomas Zimmermann, Edward Ditler
! **************************************************************************************************
   SUBROUTINE create_vcd_section(section)

      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))

      CALL section_create(section, __LOCATION__, name="VCD", &
                          description="Carry out a VCD calculation.", &
                          n_keywords=50, n_subsections=1, repeats=.FALSE.)

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the APT/AAT calculation", &
                          usage="&VCD T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="LIST_OF_ATOMS", &
                          description="Specifies a list of atoms.", &
                          usage="LIST {integer} {integer} .. {integer}", repeats=.TRUE., &
                          n_var=-1, type_of_var=integer_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DISTRIBUTED_ORIGIN", &
                          variants=(/"DO_GAUGE"/), &
                          description="Use the distributed origin (DO) gauge?", &
                          usage="DISTRIBUTED_ORIGIN T", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ORIGIN_DEPENDENT_MFP", &
                          description="Use the origin dependent MFP operator.", &
                          usage="ORIGIN_DEPENDENT_MFP T", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ORBITAL_CENTER", &
                          description="The orbital center.", &
                          usage="ORBITAL_CENTER WANNIER", &
                          default_i_val=current_orb_center_wannier, &
                          enum_c_vals=s2a("WANNIER", "COMMON", "ATOM", "BOX"), &
                          enum_desc=s2a("Use the Wannier centers.", &
                                        "Use a common center (works only for an isolate molecule).", &
                                        "Use the atoms as center.", &
                                        "Boxing."), &
                          enum_i_vals=(/current_orb_center_wannier, current_orb_center_common, &
                                        current_orb_center_atom, current_orb_center_box/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! The origin of the magnetic dipole operator (r - MAGNETIC_ORIGIN) x momentum
      CALL keyword_create(keyword, __LOCATION__, name="MAGNETIC_ORIGIN", &
                          description="Gauge origin of the magnetic dipole operator.", &
                          enum_c_vals=s2a("COM", "COAC", "USER_DEFINED", "ZERO"), &
                          enum_desc=s2a("Use Center of Mass", &
                                        "Use Center of Atomic Charges", &
                                        "Use User-defined Point", &
                                        "Use Origin of Coordinate System"), &
                          enum_i_vals=(/use_mom_ref_com, &
                                        use_mom_ref_coac, &
                                        use_mom_ref_user, &
                                        use_mom_ref_zero/), &
                          default_i_val=use_mom_ref_zero)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MAGNETIC_ORIGIN_REFERENCE", &
                          description="User-defined reference point of the magnetic dipole operator.", &
                          usage="REFERENCE_POINT x y z", &
                          repeats=.FALSE., n_var=3, type_of_var=real_t, unit_str='bohr')
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! The origin of the coordinate system
      CALL keyword_create(keyword, __LOCATION__, name="SPATIAL_ORIGIN", &
                          description="Gauge origin of the velocity gauge factor/spatial origin.", &
                          enum_c_vals=s2a("COM", "COAC", "USER_DEFINED", "ZERO"), &
                          enum_desc=s2a("Use Center of Mass", &
                                        "Use Center of Atomic Charges", &
                                        "Use User-defined Point", &
                                        "Use Origin of Coordinate System"), &
                          enum_i_vals=(/use_mom_ref_com, &
                                        use_mom_ref_coac, &
                                        use_mom_ref_user, &
                                        use_mom_ref_zero/), &
                          default_i_val=use_mom_ref_zero)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SPATIAL_ORIGIN_REFERENCE", &
                          description="User-defined reference point of the velocity gauge factor/spatial origin.", &
                          usage="REFERENCE_POINT x y z", &
                          repeats=.FALSE., n_var=3, type_of_var=real_t, unit_str='bohr')
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of the magnetic dipole moment calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "VCD", &
                                       description="Controls the printing of the APTs and AATs", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_vcd_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      calculation of induced current  DFPT
!>      Available properties : none
!> \param section the section to create
!> \author  MI/VW
! **************************************************************************************************
   SUBROUTINE create_current_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="current", &
                          description="The induced current density is calculated by DFPT.", &
                          n_keywords=4, n_subsections=1, repeats=.FALSE., &
                          citations=(/Sebastiani2001, Weber2009/))

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the induced current calculation", &
                          usage="&CURRENT T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="GAUGE", &
                          description="The gauge used to compute the induced current within GAPW.", &
                          usage="GAUGE R", &
                          default_i_val=current_gauge_r_and_step_func, &
                          enum_c_vals=s2a("R", "R_AND_STEP_FUNCTION", "ATOM"), &
                          enum_desc=s2a("Position gauge (doesnt work well).", &
                                        "Position and step function for the soft and the local parts, respectively.", &
                                        "Atoms."), &
                          enum_i_vals=(/current_gauge_r, current_gauge_r_and_step_func, current_gauge_atom/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="GAUGE_ATOM_RADIUS", &
                          description="Build the gauge=atom using only the atoms within this radius.", &
                          usage="GAUGE_ATOM_RADIUS 10.0", &
                          type_of_var=real_t, &
                          default_r_val=cp_unit_to_cp2k(value=4.0_dp, unit_str="angstrom"), &
                          unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="USE_OLD_GAUGE_ATOM", &
                          description="Use the old way to compute the gauge.", &
                          usage="USE_OLD_GAUGE_ATOM T", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ORBITAL_CENTER", &
                          description="The orbital center.", &
                          usage="ORBITAL_CENTER WANNIER", &
                          default_i_val=current_orb_center_wannier, &
                          enum_c_vals=s2a("WANNIER", "COMMON", "ATOM", "BOX"), &
                          enum_desc=s2a("Use the Wannier centers.", &
                                        "Use a common center (works only for an isolate molecule).", &
                                        "Use the atoms as center.", &
                                        "Boxing."), &
                          enum_i_vals=(/current_orb_center_wannier, current_orb_center_common, &
                                        current_orb_center_atom, current_orb_center_box/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="COMMON_CENTER", &
                          description="The common center ", usage="COMMON_CENTER 0.0 1.0 0.0", &
                          n_var=3, default_r_vals=(/0.0_dp, 0.0_dp, 0.0_dp/), type_of_var=real_t, &
                          unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NBOX", &
                          description="How many boxes along each directions ", usage="NBOX 6 6 5", &
                          n_var=3, default_i_vals=(/4, 4, 4/), type_of_var=integer_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CHI_PBC", &
                          description="Calculate the succeptibility correction to the shift with PBC", &
                          usage="CHI_PBC T", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="FORCE_NO_FULL", &
                          description="Avoid the calculation of the state dependent perturbation term, "// &
                          "even if the orbital centers are set at Wannier centers or at Atom centers", &
                          usage="FORCE_NO_FULL T", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SELECTED_STATES_ON_ATOM_LIST", &
                          description="Indexes of the atoms for selecting"// &
                          " the states to be used for the response calculations.", &
                          usage="SELECTED_STATES_ON_ATOM_LIST 1 2 10", &
                          n_var=-1, type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SELECTED_STATES_ATOM_RADIUS", &
                          description="Select all the states included in the given radius around each atoms "// &
                          "in SELECTED_STATES_ON_ATOM_LIST.", &
                          usage="SELECTED_STATES_ATOM_RADIUS 2.0", &
                          type_of_var=real_t, &
                          default_r_val=cp_unit_to_cp2k(value=4.0_dp, unit_str="angstrom"), &
                          unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART_CURRENT", &
                          description="Restart the induced current density calculation"// &
                          " from a previous run (not working yet).", &
                          usage="RESTART_CURRENT", default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of induced current density calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "CURRENT_CUBES", &
                                       description="Controls the printing of the induced current density (not working yet).", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL keyword_create(keyword, __LOCATION__, name="stride", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). You can provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components (not working yet).", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "RESPONSE_FUNCTION_CUBES", &
                                       description="Controls the printing of the response functions (not working yet).", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL keyword_create(keyword, __LOCATION__, name="stride", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). You can provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components (not working yet).", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LU_BOUNDS", &
                          variants=(/"CUBES_LU"/), &
                          description="The lower and upper index of the states to be printed as cube (not working yet).", &
                          usage="CUBES_LU_BOUNDS integer integer", &
                          n_var=2, default_i_vals=(/0, -2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LIST", &
                          description="Indexes of the states to be printed as cube files "// &
                          "This keyword can be repeated several times "// &
                          "(useful if you have to specify many indexes) (not working yet).", &
                          usage="CUBES_LIST 1 2", &
                          n_var=-1, type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_current_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>         calculation of NMR chemical shift using
!>         the induced current obtained from DFPT
!>      Available properties : none
!> \param section the section to create
!> \author  MI/VW
! **************************************************************************************************
   SUBROUTINE create_nmr_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="nmr", &
                          description="The chemical shift is calculated by DFPT.", &
                          n_keywords=5, n_subsections=1, repeats=.FALSE., &
                          citations=(/Weber2009/))

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the nmr calculation", &
                          usage="&NMR T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="INTERPOLATE_SHIFT", &
                          description="Calculate the soft part of the chemical shift by interpolation ", &
                          usage="INTERPOLATE_SHIFT T", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NICS", &
                          description="Calculate the chemical shift in a set of points"// &
                          " given from an external file", usage="NICS", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NICS_FILE_NAME", &
                          description="Name of the file with the NICS points coordinates", &
                          usage="NICS_FILE_NAME nics_file", &
                          default_lc_val="nics_file")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART_NMR", &
                          description="Restart the NMR calculation from a previous run (NOT WORKING YET)", &
                          usage="RESTART_NMR", default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SHIFT_GAPW_RADIUS", &
                          description="While computing the local part of the shift (GAPW), "// &
                          "the integration is restricted to nuclei that are within this radius.", &
                          usage="SHIFT_GAPW_RADIUS 20.0", &
                          type_of_var=real_t, &
                          default_r_val=cp_unit_to_cp2k(value=60.0_dp, unit_str="angstrom"), &
                          unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of nmr calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "RESPONSE_FUNCTION_CUBES", &
                                       description="Controls the printing of the response functions ", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL keyword_create(keyword, __LOCATION__, name="stride", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). You can provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components.", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LU_BOUNDS", &
                          variants=(/"CUBES_LU"/), &
                          description="The lower and upper index of the states to be printed as cube", &
                          usage="CUBES_LU_BOUNDS integer integer", &
                          n_var=2, default_i_vals=(/0, -2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LIST", &
                          description="Indexes of the states to be printed as cube files "// &
                          "This keyword can be repeated several times "// &
                          "(useful if you have to specify many indexes).", &
                          usage="CUBES_LIST 1 2", &
                          n_var=-1, type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "CHI_TENSOR", &
                                       description="Controls the printing of susceptibility", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "SHIELDING_TENSOR", &
                                       description="Controls the printing of the chemical shift", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="")

      CALL keyword_create(keyword, __LOCATION__, name="ATOMS_LU_BOUNDS", &
                          variants=(/"ATOMS_LU"/), &
                          description="The lower and upper atomic index for which the tensor is printed", &
                          usage="ATOMS_LU_BOUNDS integer integer", &
                          n_var=2, default_i_vals=(/0, -2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ATOMS_LIST", &
                          description="list of atoms for which the shift is printed into a file ", &
                          usage="LIST_ATOMS 1 2", n_var=-1, &
                          type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_nmr_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      calculation of NMR spin-spin coupling (implementation not operating)
!>      Available properties : none
!> \param section the section to create
!> \author  VW
! **************************************************************************************************
   SUBROUTINE create_spin_spin_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="spinspin", &
                          description="Compute indirect spin-spin coupling constants.", &
                          n_keywords=5, n_subsections=1, repeats=.FALSE.)

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the nmr calculation", &
                          usage="&SPINSPIN T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART_SPINSPIN", &
                          description="Restart the spin-spin calculation from a previous run (NOT WORKING YET)", &
                          usage="RESTART_SPINSPIN", default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ISSC_ON_ATOM_LIST", &
                          description="Atoms for which the issc is computed.", &
                          usage="ISSC_ON_ATOM_LIST 1 2 10", &
                          n_var=-1, type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_FC", &
                          description="Compute the Fermi contact contribution", &
                          usage="DO_FC F", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_SD", &
                          description="Compute the spin-dipolar contribution", &
                          usage="DO_SD F", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_PSO", &
                          description="Compute the paramagnetic spin-orbit contribution", &
                          usage="DO_PSO F", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_DSO", &
                          description="Compute the diamagnetic spin-orbit contribution (NOT YET IMPLEMENTED)", &
                          usage="DO_DSO F", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of the indirect spin-spin calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "K_MATRIX", &
                                       description="Controls the printing of the indirect spin-spin matrix", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="")

      CALL keyword_create(keyword, __LOCATION__, name="ATOMS_LIST", &
                          description="list of atoms for which the indirect spin-spin is printed into a file ", &
                          usage="LIST_ATOMS 1 2", n_var=-1, &
                          type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_spin_spin_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>         calculation of EPR using
!>         the induced current obtained from DFPT
!>      Available properties : none
!> \param section the section to create
!> \author  VW
! **************************************************************************************************
   SUBROUTINE create_epr_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection, subsubsection

      NULLIFY (keyword, print_key, subsection, subsubsection)

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="EPR", &
                          description="The g tensor is calculated by DFPT ", &
                          n_keywords=5, n_subsections=1, repeats=.FALSE., &
                          citations=(/Weber2009/))

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the epr calculation", &
                          usage="&EPR T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RESTART_EPR", &
                          description="Restart the EPR calculation from a previous run (NOT WORKING)", &
                          usage="RESTART_EPR", default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of epr calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "NABLAVKS_CUBES", &
                                       description="Controls the printing of the components of nabla v_ks ", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL keyword_create(keyword, __LOCATION__, name="stride", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). You can provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components.", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "G_TENSOR", &
                                       description="Controls the printing of the g tensor", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL create_xc_section(subsubsection)
      CALL section_add_subsection(print_key, subsubsection)
      CALL section_release(subsubsection)

      CALL keyword_create(keyword, __LOCATION__, name="GAPW_MAX_ALPHA", &
                          description="Maximum alpha of GTH potentials allowed on the soft grids ", &
                          usage="GAPW_MAX_ALPHA real", default_r_val=5.0_dp)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SOO_RHO_HARD", &
                          description="Whether or not to include the atomic parts of the density "// &
                          "in the SOO part of the g tensor", usage="SOO_RHO_HARD", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "RESPONSE_FUNCTION_CUBES", &
                                       description="Controls the printing of the response functions ", &
                                       print_level=high_print_level, add_last=add_last_numeric, filename="")
      CALL keyword_create(keyword, __LOCATION__, name="stride", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). You can provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components.", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LU_BOUNDS", &
                          variants=(/"CUBES_LU"/), &
                          description="The lower and upper index of the states to be printed as cube", &
                          usage="CUBES_LU_BOUNDS integer integer", &
                          n_var=2, default_i_vals=(/0, -2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="CUBES_LIST", &
                          description="Indexes of the states to be printed as cube files "// &
                          "This keyword can be repeated several times "// &
                          "(useful if you have to specify many indexes).", &
                          usage="CUBES_LIST 1 2", &
                          n_var=-1, type_of_var=integer_t, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_epr_section

! **************************************************************************************************
!> \brief creates the input structure used to activate
!>      calculation of polarizability tensor DFPT
!>      Available properties : none
!> \param section the section to create
!> \author SL
! **************************************************************************************************
   SUBROUTINE create_polarizability_section(section)

      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword, print_key, subsection)

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="POLAR", &
                          description="Compute polarizabilities.", &
                          n_keywords=5, n_subsections=1, repeats=.FALSE., &
                          citations=(/Putrino2002/))

      CALL keyword_create(keyword, __LOCATION__, name="_SECTION_PARAMETERS_", &
                          description="controls the activation of the polarizability calculation", &
                          usage="&POLAR T", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_RAMAN", &
                          description="Compute the electric-dipole--electric-dipole polarizability", &
                          usage="DO_RAMAN F", &
                          citations=(/Luber2014/), &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="PERIODIC_DIPOLE_OPERATOR", &
                          description="Type of dipole operator: Berry phase(T) or Local(F)", &
                          usage="PERIODIC_DIPOLE_OPERATOR T", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="print results of the polarizability calculation", &
                          repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "POLAR_MATRIX", &
                                       description="Controls the printing of the polarizabilities", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="")

      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_interp_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_polarizability_section

! **************************************************************************************************
!> \brief creates the section for electron transfer coupling
!> \param section ...
!> \author fschiff
! **************************************************************************************************
   SUBROUTINE create_et_coupling_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      NULLIFY (keyword)
      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="ET_COUPLING", &
                          description="specifies the two constraints/restraints for extracting ET coupling elements", &
                          n_keywords=1, n_subsections=4, repeats=.FALSE., citations=(/Kondov2007, Futera2017/))

      NULLIFY (subsection)
      CALL create_ddapc_restraint_section(subsection, "DDAPC_RESTRAINT_A")
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_ddapc_restraint_section(subsection, "DDAPC_RESTRAINT_B")
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      NULLIFY (subsection)
      CALL create_projection(subsection, "PROJECTION")
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL keyword_create(keyword, __LOCATION__, name="TYPE_OF_CONSTRAINT", &
                          description="Specifies the type of constraint", &
                          usage="TYPE_OF_CONSTRAINT DDAPC", &
                          enum_c_vals=s2a("NONE", "DDAPC"), &
                          enum_i_vals=(/do_no_et, do_et_ddapc/), &
                          enum_desc=s2a("NONE", "DDAPC Constraint"), &
                          default_i_val=do_no_et)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (print_key)
      CALL cp_print_key_section_create(print_key, __LOCATION__, "PROGRAM_RUN_INFO", &
                                       description="Controls the printing basic info about the method", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="__STD_OUT__")
      CALL section_add_subsection(section, print_key)
      CALL section_release(print_key)

   END SUBROUTINE create_et_coupling_section

! **************************************************************************************************
!> \brief defines input sections for specification of Hilbert space partitioning
!>        in projection-operator approach of electronic coupling calulation
!> \param section pointer to the section data structure
!> \param section_name name of the projection section
!> \author Z. Futera (02.2017)
! **************************************************************************************************
   SUBROUTINE create_projection(section, section_name)

      ! Routine arguments
      TYPE(section_type), POINTER                        :: section
      CHARACTER(len=*), INTENT(in)                       :: section_name

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, section_block, section_print

! Routine name for dubug purposes

      ! Sanity check
      CPASSERT(.NOT. ASSOCIATED(section))

      ! Initialization
      NULLIFY (keyword)
      NULLIFY (print_key)
      NULLIFY (section_block)
      NULLIFY (section_print)

      ! Input-file section definition
      CALL section_create(section, __LOCATION__, name=TRIM(ADJUSTL(section_name)), &
                          description="Projection-operator approach fo ET coupling calculation", &
                          n_keywords=0, n_subsections=2, repeats=.FALSE.)

      ! Subsection #0: Log printing
      CALL cp_print_key_section_create(print_key, __LOCATION__, 'PROGRAM_RUN_INFO', &
                                       description="Controls printing of data and informations to log file", &
                                       print_level=low_print_level, filename="__STD_OUT__")
      CALL section_add_subsection(section, print_key)
      CALL section_release(print_key)

      ! Subsection #1: Atomic blocks
      CALL section_create(section_block, __LOCATION__, name='BLOCK', &
                          description="Part of the system (donor, acceptor, bridge,...)", &
                          n_keywords=2, n_subsections=1, repeats=.TRUE.)
      CALL section_add_subsection(section, section_block)

      ! S#1 - Keyword #1: Atom IDs defining a Hilbert space block
      CALL keyword_create(keyword, __LOCATION__, name='ATOMS', &
                          description="Array of atom IDs in the system part", &
                          usage="ATOMS {integer} {integer} .. {integer}", &
                          n_var=-1, type_of_var=integer_t, repeats=.FALSE.)
      CALL section_add_keyword(section_block, keyword)
      CALL keyword_release(keyword)

      ! S#1 - Keyword #1: Atom IDs defining a Hilbert space block
      CALL keyword_create(keyword, __LOCATION__, name='NELECTRON', &
                          description="Number of electrons expected in the system part", &
                          usage="NELECTRON {integer}", default_i_val=0)
      CALL section_add_keyword(section_block, keyword)
      CALL keyword_release(keyword)

      ! S#1 - Subsection #1: Printing setting
      CALL section_create(section_print, __LOCATION__, name='PRINT', &
                          description="Possible printing options in ET system part", &
                          n_keywords=0, n_subsections=0, repeats=.FALSE.)
      CALL section_add_subsection(section_block, section_print)

      ! S#1 - S#1 - Keyword #1: MO coefficient on specific atom
      CALL keyword_create(keyword, __LOCATION__, name='MO_COEFF_ATOM', &
                          description="Print out MO coeffiecients on given atom", &
                          usage="MO_COEFF_ATOM {integer} {integer} .. {integer}", &
                          type_of_var=integer_t, n_var=-1, repeats=.TRUE.)
      CALL section_add_keyword(section_print, keyword)
      CALL keyword_release(keyword)

      ! S#1 - S#1 - Keyword #1: MO coefficient of specific state
      CALL keyword_create(keyword, __LOCATION__, name='MO_COEFF_ATOM_STATE', &
                          description="Print out MO coeffiecients of specific state", &
                          usage="MO_COEFF_ATOM_STATE {integer} {integer} .. {integer}", &
                          type_of_var=integer_t, n_var=-1, repeats=.TRUE.)
      CALL section_add_keyword(section_print, keyword)
      CALL keyword_release(keyword)

      ! S#1 - S#1 - Subsection #1: Saving MOs to CUBE files
      CALL cp_print_key_section_create(print_key, __LOCATION__, 'MO_CUBES', &
                                       description="Controls saving of MO cube files", &
                                       print_level=high_print_level, filename="")

      ! S#1 - S#1 - S#1 - Keyword #1: Stride
      CALL keyword_create(keyword, __LOCATION__, name='STRIDE', &
                          description="The stride (X,Y,Z) used to write the cube file", &
                          usage="STRIDE {integer} {integer} {integer}", n_var=-1, &
                          default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      ! S#1 - S#1 - S#1 - Keyword #2: List of MO IDs
      CALL keyword_create(keyword, __LOCATION__, name='MO_LIST', &
                          description="Indices of molecular orbitals to save", &
                          usage="MO_LIST {integer} {integer} .. {integer}", &
                          type_of_var=integer_t, n_var=-1, repeats=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      ! S#1 - S#1 - S#1 - Keyword #2: Number of unoccupied states
      CALL keyword_create(keyword, __LOCATION__, name='NLUMO', &
                          description="Number of unoccupied molecular orbitals to save", &
                          usage="NLUMO {integer}", default_i_val=1)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      ! S#1 - S#1 - S#1 - Keyword #3: Number of occupied states
      CALL keyword_create(keyword, __LOCATION__, name='NHOMO', &
                          description="Number of occupied molecular orbitals to save", &
                          usage="NHOMO {integer}", default_i_val=1)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(section_print, print_key)
      CALL section_release(print_key)

      ! S#1 - S#1 - Clean
      CALL section_release(section_print)

      ! S#1 - Clean
      CALL section_release(section_block)

      ! S#1 - Subsection #1: Printing setting
      CALL section_create(section_print, __LOCATION__, name='PRINT', &
                          description="Possible printing options in ET", &
                          n_keywords=0, n_subsections=0, repeats=.FALSE.)
      CALL section_add_subsection(section, section_print)

      ! Print couplings
      CALL cp_print_key_section_create(print_key, __LOCATION__, 'COUPLINGS', &
                                       description="Controls printing couplings onto file", &
                                       print_level=low_print_level, filename="")

      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(section_print, print_key)
      CALL section_release(print_key)

      CALL section_release(section_print)

   END SUBROUTINE create_projection

! **************************************************************************************************
!> \brief creates an input section for tddfpt calculation
!> \param section section to create
!> \par History
!>    * 05.2016 forked from create_tddfpt_section [Sergey Chulkov]
!>    * 08.2016 moved from module input_cp2k_dft [Sergey Chulkov]
! **************************************************************************************************
   SUBROUTINE create_tddfpt2_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="TDDFPT", &
                          description="Parameters needed to set up the Time-Dependent "// &
                          "Density Functional Perturbation Theory. "// &
                          "Current implementation works for hybrid functionals. "// &
                          "Can be used with Gaussian and Plane Waves (GPW) method only.", &
                          n_keywords=12, n_subsections=4, repeats=.FALSE., &
                          citations=(/Iannuzzi2005/))

      NULLIFY (keyword, print_key, subsection)

      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the TDDFPT procedure", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! Integer
      CALL keyword_create(keyword, __LOCATION__, name="NSTATES", &
                          description="Number of excited states to converge.", &
                          n_var=1, type_of_var=integer_t, &
                          default_i_val=1)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MAX_ITER", &
                          description="Maximal number of iterations to be performed.", &
                          n_var=1, type_of_var=integer_t, &
                          default_i_val=50)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MAX_KV", &
                          description="Maximal number of Krylov space vectors. "// &
                          "Davidson iterations will be restarted upon reaching this limit.", &
                          n_var=1, type_of_var=integer_t, &
                          default_i_val=5000)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NLUMO", &
                          description="Number of unoccupied orbitals to consider. "// &
                          "Default is to use all unoccupied orbitals (-1).", &
                          n_var=1, type_of_var=integer_t, &
                          default_i_val=-1)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NPROC_STATE", &
                          description="Number of MPI processes to be used per excited state. "// &
                          "Default is to use all processors (0).", &
                          n_var=1, type_of_var=integer_t, &
                          default_i_val=0)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! kernel type
      CALL keyword_create(keyword, __LOCATION__, name="KERNEL", &
                          description="Options to compute the kernel", &
                          usage="KERNEL FULL", &
                          enum_c_vals=s2a("FULL", "sTDA", "NONE"), &
                          enum_i_vals=(/tddfpt_kernel_full, tddfpt_kernel_stda, tddfpt_kernel_none/), &
                          default_i_val=tddfpt_kernel_full)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="OE_CORR", &
                          description="Orbital energy correction potential.", &
                          enum_c_vals=s2a("NONE", "LB94", "GLLB", "SAOP", "SHIFT"), &
                          enum_i_vals=(/oe_none, oe_lb, oe_gllb, oe_saop, oe_shift/), &
                          enum_desc=s2a("No orbital correction scheme is used", &
                                        "van Leeuwen and Baerends. PRA, 49:2421, 1994", &
                                        "Gritsenko, van Leeuwen, van Lenthe, Baerends. PRA, 51:1944, 1995", &
                                        "Gritsenko, Schipper, Baerends. Chem. Phys. Lett., 302:199, 1999", &
                                        "Constant shift of virtual and/or open-shell orbitals"), &
                          default_i_val=oe_none)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! SHIFTS
      CALL keyword_create(keyword, __LOCATION__, name="EV_SHIFT", &
                          variants=s2a("VIRTUAL_SHIFT"), &
                          description="Constant shift of virtual state eigenvalues.", &
                          usage="EV_SHIFT 0.500", &
                          n_var=1, type_of_var=real_t, &
                          unit_str="eV", &
                          default_r_val=0.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)
      !
      CALL keyword_create(keyword, __LOCATION__, name="EOS_SHIFT", &
                          variants=s2a("OPEN_SHELL_SHIFT"), &
                          description="Constant shift of open shell eigenvalues.", &
                          usage="EOS_SHIFT 0.200", &
                          n_var=1, type_of_var=real_t, &
                          unit_str="eV", &
                          default_r_val=0.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! Real
      CALL keyword_create(keyword, __LOCATION__, name="CONVERGENCE", &
                          description="Target accuracy for excited state energies.", &
                          n_var=1, type_of_var=real_t, unit_str="hartree", &
                          default_r_val=1.0e-5_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MIN_AMPLITUDE", &
                          description="The smallest excitation amplitude to print.", &
                          n_var=1, type_of_var=real_t, &
                          default_r_val=5.0e-2_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ORTHOGONAL_EPS", &
                          description="The largest possible overlap between the ground state and "// &
                          "orthogonalised excited state wave-functions. Davidson iterations "// &
                          "will be restarted when the overlap goes beyond this threshold in "// &
                          "order to prevent numerical instability.", &
                          n_var=1, type_of_var=real_t, &
                          default_r_val=1.0e-4_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! Logical
      CALL keyword_create(keyword, __LOCATION__, name="RESTART", &
                          description="Restart the TDDFPT calculation if a restart file exists", &
                          n_var=1, type_of_var=logical_t, &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="RKS_TRIPLETS", &
                          description="Compute triplet excited states using spin-unpolarised molecular orbitals.", &
                          n_var=1, type_of_var=logical_t, &
                          default_l_val=.FALSE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ADMM_KERNEL_XC_CORRECTION", &
                          description="Use/Ignore ADMM correction xc functional for TD kernel. "// &
                          "XC correction functional is defined in ground state XC section.", &
                          n_var=1, type_of_var=logical_t, &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ADMM_KERNEL_CORRECTION_SYMMETRIC", &
                          description="ADMM correction functional in kernel is applied symmetrically. "// &
                          "Original implementation is using a non-symmetric formula.", &
                          n_var=1, type_of_var=logical_t, &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_LRIGPW", &
                          description="Local resolution of identity for Coulomb contribution.", &
                          n_var=1, type_of_var=logical_t, &
                          default_l_val=.FALSE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="AUTO_BASIS", &
                          description="Specify size of automatically generated auxiliary basis sets: "// &
                          "Options={small,medium,large,huge}", &
                          usage="AUTO_BASIS {basis_type} {basis_size}", &
                          type_of_var=char_t, repeats=.TRUE., n_var=-1, default_c_vals=(/"X", "X"/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! Strings
      CALL keyword_create(keyword, __LOCATION__, name="WFN_RESTART_FILE_NAME", &
                          variants=(/"RESTART_FILE_NAME"/), &
                          description="Name of the wave function restart file, may include a path."// &
                          " If no file is specified, the default is to open the file as generated by"// &
                          " the wave function restart print key.", &
                          usage="WFN_RESTART_FILE_NAME <FILENAME>", &
                          type_of_var=lchar_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! DIPOLE subsection
      CALL section_create(subsection, __LOCATION__, name="DIPOLE_MOMENTS", &
                          description="Parameters to compute oscillator strengths in the dipole approximation.", &
                          n_keywords=3, n_subsections=0, repeats=.FALSE.)

      CALL keyword_create(keyword, __LOCATION__, name="DIPOLE_FORM", &
                          description="Form of dipole transition integrals.", &
                          enum_c_vals=s2a("BERRY", "LENGTH", "VELOCITY"), &
                          enum_desc=s2a("Based on Berry phase formula (valid for fully periodic molecular systems only)", &
                                        "Length form &lang; i | r | j &rang; (valid for non-periodic molecular systems only)", &
                                        "Velocity form &lang; i | d/dr | j &rang;"), &
                          enum_i_vals=(/tddfpt_dipole_berry, tddfpt_dipole_length, tddfpt_dipole_velocity/), &
                          default_i_val=tddfpt_dipole_velocity)
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="REFERENCE", &
                          description="Reference point to calculate electric "// &
                          "dipole moments using the dipole integrals in the length form.", &
                          enum_c_vals=s2a("COM", "COAC", "USER_DEFINED", "ZERO"), &
                          enum_desc=s2a("Use Center of Mass", &
                                        "Use Center of Atomic Charges", &
                                        "Use User-defined Point", &
                                        "Use Origin of Coordinate System"), &
                          enum_i_vals=(/use_mom_ref_com, &
                                        use_mom_ref_coac, &
                                        use_mom_ref_user, &
                                        use_mom_ref_zero/), &
                          default_i_val=use_mom_ref_com)
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="REFERENCE_POINT", &
                          description="User-defined reference point.", &
                          usage="REFERENCE_POINT x y z", &
                          repeats=.FALSE., n_var=3, type_of_var=real_t, unit_str='bohr')
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! SOC functional

      CALL section_create(subsection, __LOCATION__, name="SOC", &
                          description="Is jet to be implemented", &
                          n_keywords=2, n_subsections=0, repeats=.FALSE.)

      CALL keyword_create(keyword, __LOCATION__, name="EPS_FILTER", &
                          variants=s2a("EPS_FILTER_MATRIX"), &
                          description="The threshold used for sparse matrix operations", &
                          usage="EPS_FILTER {real}", &
                          type_of_var=real_t, &
                          default_r_val=1.0E-10_dp)
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="GRID", &
                          variants=(/"ATOMIC_GRID"/), &
                          description="Specification of the atomic angular and radial grids for "// &
                          "a atomic kind. This keyword must be repeated for all kinds!  "// &
                          "Usage: GRID < LEBEDEV_GRID > < RADIAL_GRID >", &
                          usage="GRID {string} {integer} {integer}", &
                          n_var=3, type_of_var=char_t, repeats=.TRUE.)
      CALL section_add_keyword(subsection, keyword)
      CALL keyword_release(keyword)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! kernel XC functional
      CALL create_xc_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! MGRID subsection
      CALL create_mgrid_section(subsection, create_subsections=.FALSE.)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! sTDA subsection
      CALL create_stda_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! LRI subsection
      CALL create_lrigpw_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! LINRES section
      CALL create_linres_section(subsection, create_subsections=.FALSE., default_set_tdlr=.TRUE.)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      ! PRINT subsection
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="Printing of information during the TDDFT run.", repeats=.FALSE.)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="PROGRAM_BANNER", &
                                       description="Controls the printing of the banner for TDDFPT program", &
                                       print_level=silent_print_level, filename="__STD_OUT__")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="GUESS_VECTORS", &
                                       description="Controls the printing of initial guess vectors.", &
                                       print_level=low_print_level, filename="__STD_OUT__")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="ITERATION_INFO", &
                                       description="Controls the printing of basic iteration information "// &
                                       "during the TDDFT run.", &
                                       print_level=low_print_level, add_last=add_last_numeric, filename="__STD_OUT__")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="DETAILED_ENERGY", &
                                       description="Controls the printing of detailed energy information "// &
                                       "during the TDDFT run.", &
                                       print_level=medium_print_level, add_last=add_last_numeric, filename="__STD_OUT__")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="BASIS_SET_FILE", &
                                       description="Controls the printing of a file with all basis sets used.", &
                                       print_level=debug_print_level, filename="BASIS_SETS")
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="RESTART", &
                                       description="Controls the dumping of the MO restart file during TDDFPT. "// &
                                       "By default keeps a short history of three restarts.", &
                                       print_level=low_print_level, common_iter_levels=3, &
                                       each_iter_names=s2a("TDDFT_SCF"), each_iter_values=(/10/), &
                                       add_last=add_last_numeric, filename="RESTART")
      CALL keyword_create(keyword, __LOCATION__, name="BACKUP_COPIES", &
                          description="Specifies the maximum number of backup copies.", &
                          usage="BACKUP_COPIES {int}", &
                          default_i_val=1)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="NTO_ANALYSIS", &
                                       description="Perform a natural transition orbital analysis.", &
                                       print_level=medium_print_level)
      CALL keyword_create(keyword, __LOCATION__, name="THRESHOLD", &
                          description="Threshold for sum of NTO eigenvalues considered", &
                          usage="Threshold 0.95", &
                          n_var=1, &
                          type_of_var=real_t, &
                          default_r_val=0.975_dp)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="INTENSITY_THRESHOLD", &
                          description="Threshold for oscillator strength to screen states.", &
                          usage="Intensity_threshold 0.01", &
                          n_var=1, &
                          type_of_var=real_t, &
                          default_r_val=0.0_dp)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="STATE_LIST", &
                          description="Specifies a list of states for the NTO calculations.", &
                          usage="STATE_LIST {integer} {integer} .. {integer}", &
                          n_var=-1, type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="CUBE_FILES", &
                          description="Print NTOs on Cube Files", &
                          usage="CUBE_FILES {logical}", repeats=.FALSE., n_var=1, &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE., type_of_var=logical_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="STRIDE", &
                          description="The stride (X,Y,Z) used to write the cube file "// &
                          "(larger values result in smaller cube files). Provide 3 numbers (for X,Y,Z) or"// &
                          " 1 number valid for all components.", &
                          usage="STRIDE 2 2 2", n_var=-1, default_i_vals=(/2, 2, 2/), type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="APPEND", &
                          description="append the cube files when they already exist", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, "MOS_MOLDEN", &
                                       description="Write the NTO in Molden file format, for visualisation.", &
                                       print_level=debug_print_level + 1, add_last=add_last_numeric, filename="MOS")
      CALL keyword_create(keyword, __LOCATION__, name="NDIGITS", &
                          description="Specifies the number of significant digits retained. 3 is OK for visualization.", &
                          usage="NDIGITS {int}", &
                          default_i_val=3)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="GTO_KIND", &
                          description="Representation of Gaussian-type orbitals", &
                          default_i_val=gto_spherical, &
                          enum_c_vals=s2a("CARTESIAN", "SPHERICAL"), &
                          enum_desc=s2a( &
                          "Cartesian Gaussian orbitals. Use with caution", &
                          "Spherical Gaussian orbitals. Incompatible with VMD"), &
                          enum_i_vals=(/gto_cartesian, gto_spherical/))
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="NAMD_PRINT", &
                                       description="Controls the printout required for NAMD with NEWTONX.", &
                                       print_level=debug_print_level + 1, filename="CP2K_NEWTONX")
      CALL keyword_create(keyword, __LOCATION__, name="PRINT_VIRTUALS", &
                          description="Print occupied AND virtual molecular orbital coefficients", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="PRINT_PHASES", &
                          description="Print phases of occupied and virtuals MOs.", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="SCALE_WITH_PHASES", &
                          description="Scale ES eigenvectors with phases of occupied and virtuals MOs.", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      !! SOC PRINT SECTION
      CALL cp_print_key_section_create(print_key, __LOCATION__, name="SOC_PRINT", &
                                       description="Controls the printout of the tddfpt2_soc modul", &
                                       print_level=debug_print_level + 1, filename="SOC")
      CALL keyword_create(keyword, __LOCATION__, name="UNIT_eV", &
                          description="Will detrement if output in eVolt will be printef.", &
                          default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="UNIT_wn", &
                          description="Will detrement if output in wavenumbers will be printed.", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="SPLITTING", &
                          description="Will add the SOC-Splitting as additional output", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="SOME", &
                          description="Will add the SOC-Matrix as additional output in a different file", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL cp_print_key_section_create(print_key, __LOCATION__, name="FORCES", &
                                       description="Controls the calculation and printing of excited state forces. "// &
                                       "This needs a RUN_TYPE that includes force evaluation, e.g. ENERGY_FORCE", &
                                       print_level=debug_print_level, filename="TDFORCE")
      CALL keyword_create(keyword, __LOCATION__, name="LIST", &
                          description="Specifies a list of states for the force calculations.", &
                          usage="LIST {integer} {integer} .. {integer}", repeats=.TRUE., &
                          n_var=-1, type_of_var=integer_t)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL keyword_create(keyword, __LOCATION__, name="THRESHOLD", &
                          description="Threshold for oszillator strength to screen states.", &
                          usage="Threshold 0.01", &
                          n_var=1, &
                          type_of_var=real_t, &
                          default_r_val=0.0_dp)
      CALL section_add_keyword(print_key, keyword)
      CALL keyword_release(keyword)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_tddfpt2_section

! **************************************************************************************************
!> \brief creates the stda input section (simplified Tamm Dancoff Approximation)
!> \param section the section to create
! **************************************************************************************************
   SUBROUTINE create_stda_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="sTDA", &
                          description="parameters needed and setup for sTDA calculations", &
                          n_keywords=3, n_subsections=0, repeats=.FALSE.)
      NULLIFY (keyword)

      CALL keyword_create(keyword, __LOCATION__, name="FRACTION", &
                          variants=(/"HFX_FRACTION"/), &
                          description="The fraction of TB Hartree-Fock exchange to use in the Kernel. "// &
                          "0.0 implies no HFX part is used in the kernel. ", &
                          usage="FRACTION 0.0", default_r_val=0.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! even if scaling parameter for exchange FRACTION (see above) is zero, the semi-empirical electron repulsion
      ! operator for exchange is not, so that a keyword is required to switch off sTDA exchange (if wanted)
      CALL keyword_create(keyword, __LOCATION__, name="DO_EXCHANGE", &
                          description="Explicitly including or switching off sTDA exchange", &
                          usage="DO_EXCHANGE", default_l_val=.TRUE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="DO_EWALD", &
                          description="Use Ewald type method for Coulomb interaction", &
                          usage="DO_EWALD", default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="EPS_TD_FILTER", &
                          description="Threshold for filtering the transition density matrix", &
                          usage="EPS_TD_FILTER epsf", default_r_val=1.e-10_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MATAGA_NISHIMOTO_CEXP", &
                          description="Exponent used in Mataga-Nishimoto formula for Coulomb (alpha). "// &
                          "Default value is method dependent!", &
                          usage="MATAGA_NISHIMOTO_CEXP cexp", default_r_val=-99.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MATAGA_NISHIMOTO_XEXP", &
                          description="Exponent used in Mataga-Nishimoto formula for Exchange (beta). "// &
                          "Default value is method dependent!", &
                          usage="MATAGA_NISHIMOTO_XEXP xexp", default_r_val=-99.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="COULOMB_SR_CUT", &
                          description="Maximum range of short range part of Coulomb interaction.", &
                          usage="COULOMB_SR_CUT rcut", default_r_val=20.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="COULOMB_SR_EPS", &
                          description="Threshold for short range part of Coulomb interaction.", &
                          usage="COULOMB_SR_EPS sreps", default_r_val=1.e-03_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

   END SUBROUTINE create_stda_section

! **************************************************************************************************
!> \brief creates an input section for electronic band structure calculations
!> \param section section to create
!> \par History
!>    * 07.2023 created [Jan Wilhelm]
! **************************************************************************************************
   SUBROUTINE create_bandstructure_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: subsection

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="BANDSTRUCTURE", &
                          description="Parameters needed to set up a calculation for "// &
                          "electronic level energies of molecules and the electronic band "// &
                          "structure of materials from post-SCF schemes (GW, perturbative "// &
                          "spin-orbit coupling). Also, the density of states (DOS), "// &
                          "projected density of states (PDOS), local density of states (LDOS), "// &
                          "local valence band maximum (LVBM), local conduction band minimum "// &
                          "(LCBM) and local band gap can be calculated. Please note that "// &
                          "all methods in this section start from a Gamma-only DFT SCF. "// &
                          "You need to make sure that the cell chosen in the DFT SCF is "// &
                          "converged in the cell size. Band structures are computed "// &
                          "for the primitive cell (i.e. the smallest possible unit cell of "// &
                          "the input structure which is detected automatically). Moreover, "// &
                          "spin-orbit coupling (SOC) on eigenvalues and band structures is "// &
                          "available using Hartwigsen-Goedecker-Hutter "// &
                          "pseudopotentials.", &
                          n_keywords=1, n_subsections=1, repeats=.FALSE.)

      NULLIFY (keyword, subsection)
      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the band structure calculation.", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      ! here we generate a subsection for getting a k-point path for the bandstructure
      CALL create_kpoint_set_section(subsection, "BANDSTRUCTURE_PATH")
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_gw_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_soc_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

      CALL create_dos_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_bandstructure_section

! **************************************************************************************************
!> \brief creates an input section for a GW calculation for the electronic band structure
!> \param section section to create
!> \par History
!>    * 07.2023 created [Jan Wilhelm]
! **************************************************************************************************
   SUBROUTINE create_gw_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: print_key, subsection

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="GW", &
                          description="Parameters needed to set up a GW calculation for "// &
                          "electronic level energies of molecules and the band structure of "// &
                          "materials (currently only 2D materials tested). For the GW "// &
                          "algorithm for molecules, see "// &
                          "<https://doi.org/10.1021/acs.jctc.0c01282>. "// &
                          "For 2D materials, see <http://arxiv.org/abs/2306.16066>.", &
                          n_keywords=1, n_subsections=1, repeats=.FALSE.)

      NULLIFY (keyword)
      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the GW calculation.", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="NUM_TIME_FREQ_POINTS", &
                          description="Number of discrete points for the imaginary-time "// &
                          "grid and the imaginary-frequency grid. The more points, the more "// &
                          "precise is the calculation. Typically, 10 points are good "// &
                          "for 0.1 eV precision of band structures and molecular energy "// &
                          "levels, 20 points for 0.03 eV precision, "// &
                          "and 30 points for 0.01 eV precision, see Table I in "// &
                          "<https://doi.org/10.1021/acs.jctc.0c01282>. GW computation time "// &
                          "increases linearly with `NUM_TIME_FREQ_POINTS`.", &
                          usage="NUM_TIME_FREQ_POINTS 30", &
                          default_i_val=30)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="EPS_FILTER", &
                          description="Determines a threshold for the DBCSR based sparse "// &
                          "multiplications. Normally, `EPS_FILTER` determines accuracy "// &
                          "and timing of low-scaling GW calculations. (Lower filter means "// &
                          "higher numerical precision, but higher computational cost.)", &
                          usage="EPS_FILTER 1.0E-6", &
                          default_r_val=1.0E-8_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="MEMORY_PER_PROC", &
                          description="Specify the available memory per MPI process. Set "// &
                          "`MEMORY_PER_PROC` as accurately as possible for good performance. If "// &
                          "`MEMORY_PER_PROC` is set lower as the actually available "// &
                          "memory per MPI process, the performance will be "// &
                          "bad; if `MEMORY_PER_PROC` is set higher as the actually "// &
                          "available memory per MPI process, the program might run out of "// &
                          "memory. You can calculate `MEMORY_PER_PROC` as follows: "// &
                          "Get the memory per node on your machine, mem_per_node "// &
                          "(for example, from a supercomputer website, typically between "// &
                          "100 GB and 2 TB), get the number of "// &
                          "MPI processes per node, n_MPI_proc_per_node"// &
                          " (for example from your run-script; if you "// &
                          "use slurm, the number behind '--ntasks-per-node' is the number "// &
                          "of MPI processes per node). Then calculate "// &
                          "`MEMORY_PER_PROC` = mem_per_node / n_MPI_proc_per_node "// &
                          "(typically between 2 GB and 50 GB). Unit of keyword: Gigabyte (GB).", &
                          usage="MEMORY_PER_PROC 16", &
                          default_r_val=2.0_dp)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="APPROX_KP_EXTRAPOL", &
                          description="If true, use only a 4x4 kpoint mesh for frequency "// &
                          "points $\omega_j, j \ge 2$ (instead of a 4x4 and 6x6 k-point mesh). "// &
                          "The k-point extrapolation of $W_{PQ}(i\omega_j,\mathbf{q})$ "// &
                          "is done approximately from $W_{PQ}(i\omega_1,\mathbf{q})$.", &
                          usage="APPROX_KP_EXTRAPOL", &
                          default_l_val=.FALSE., lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection, print_key)
      CALL section_create(subsection, __LOCATION__, name="PRINT", &
                          description="Printing of GW restarts.", &
                          n_keywords=0, n_subsections=1, repeats=.FALSE.)
      CALL cp_print_key_section_create(print_key, __LOCATION__, "RESTART", &
                                       description="Controls the printing of restart files "// &
                                       "for χ, W, Σ.", &
                                       filename="", print_level=low_print_level, &
                                       common_iter_levels=3)
      CALL section_add_subsection(subsection, print_key)
      CALL section_release(print_key)

      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_gw_section

! **************************************************************************************************
!> \brief creates an input section for calculation SOC for the electronic band structure
!> \param section section to create
!> \par History
!>    * 09.2023 created [Jan Wilhelm]
! **************************************************************************************************
   SUBROUTINE create_soc_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="SOC", &
                          description="Switch on or off spin-orbit coupling. Use SOC "// &
                          "parameters from non-local pseudopotentials as given in "// &
                          "Hartwigsen, Goedecker, Hutter, Eq.(18), (19), "// &
                          "<https://doi.org/10.1103/PhysRevB.58.3641>, "// &
                          "$V_{\mu\nu}^{\mathrm{SOC}, (\alpha)} = "// &
                          "(\hbar/2) \langle \phi_\mu | \sum_l \Delta "// &
                          "V_l^\mathrm{SO}(\mathbf{r},\mathbf{r}') L^{(\alpha)} | \phi_\nu \rangle, "// &
                          "\alpha = x, y, z$.", &
                          n_keywords=1, n_subsections=1, repeats=.FALSE.)

      NULLIFY (keyword)
      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the SOC calculation.", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ENERGY_WINDOW", &
                          description="Apply SOC only for states with eigenvalues in the "// &
                          "interval $[\varepsilon_\mathrm{VBM}-E_\mathrm{window}/2, "// &
                          "\varepsilon_\mathrm{CBM}+E_\mathrm{window}/2]$. Might be necessary "// &
                          "to use for large systems to prevent numerical instabilities.", &
                          usage="ENERGY_WINDOW 5.0", &
                          default_r_val=cp_unit_to_cp2k(value=-1.0_dp, unit_str="eV"), &
                          unit_str="eV")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

   END SUBROUTINE create_soc_section

! **************************************************************************************************
!> \brief input section for computing the density of states and the projected density of states
!> \param section section to create
!> \par History
!>    * 09.2023 created [Jan Wilhelm]
! **************************************************************************************************
   SUBROUTINE create_dos_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword
      TYPE(section_type), POINTER                        :: subsection

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="DOS", &
                          description="Parameters needed to calculate the density of states "// &
                          "(DOS) and the projected density of states (PDOS).", &
                          n_keywords=1, n_subsections=1, repeats=.FALSE.)

      NULLIFY (keyword)
      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the DOS calculation.", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ENERGY_WINDOW", &
                          description="Print DOS and PDOS in the energy window "// &
                          "$[\varepsilon_\mathrm{VBM}-E_\mathrm{window}/2,  "// &
                          "\varepsilon_\mathrm{CBM}+E_\mathrm{window}/2]$,"// &
                          " where VBM is the valence "// &
                          "band maximum (or highest occupied molecular orbital, HOMO, for "// &
                          "molecules) and CBM the conduction band minimum (or lowest "// &
                          "unoccupied molecular orbital, LUMO, for molecules).", &
                          usage="ENERGY_WINDOW 5.0", &
                          default_r_val=cp_unit_to_cp2k(value=10.0_dp, unit_str="eV"), &
                          unit_str="eV")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="ENERGY_STEP", &
                          description="Resolution of the energy E when computing the $\rho(E)$.", &
                          usage="ENERGY_STEP 0.01", &
                          default_r_val=cp_unit_to_cp2k(value=0.01_dp, unit_str="eV"), &
                          unit_str="eV")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="BROADENING", &
                          description="Broadening α in Gaussians used in the DOS; "// &
                          "$\rho(E) = \sum_n \exp(((E-\varepsilon_n)/\alpha)^2)/("// &
                          " \sqrt{2\pi} \alpha)$.", &
                          usage="BROADENING 0.01", &
                          default_r_val=cp_unit_to_cp2k(value=0.01_dp, unit_str="eV"), &
                          unit_str="eV")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create( &
         keyword, __LOCATION__, name="KPOINTS", &
         description="Monkhorst-Pack k-point mesh of size N_x, N_y, N_z for calculating "// &
         "the density of states (DOS). In GW, the KPOINT_DOS mesh is thus used as k-point "// &
         "mesh for the self-energy. For non-periodic directions α, choose N_α = 1. "// &
         "Automatic choice of the k-point mesh for negative "// &
         "values, e.g. KPOINTS_DOS -1 -1 -1 (automatic choice: N_α = 1 in non-periodic "// &
         "direction, 8 k-points in periodic direction). If you like to compute a "// &
         "band structure along a k-path, you can specify the k-path in "// &
         "&KPOINT_SET.", &
         usage="KPOINTS N_x  N_y  N_z", &
         n_var=3, type_of_var=integer_t, default_i_vals=(/-1, -1, -1/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      NULLIFY (subsection)
      CALL create_ldos_section(subsection)
      CALL section_add_subsection(section, subsection)
      CALL section_release(subsection)

   END SUBROUTINE create_dos_section

! **************************************************************************************************
!> \brief ...
!> \param section ...
! **************************************************************************************************
   SUBROUTINE create_ldos_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="LDOS", &
                          description="Parameters needed to calculate the local density "// &
                          "of states (LDOS).  "// &
                          "The LDOS is computed as $\rho(\mathbf{r},E) = "// &
                          "\sum\limits_{n,\mathbf{k}}"// &
                          " |\psi_{n\mathbf{k}}(r)|^2\, w_\mathbf{k}\, g(E-\varepsilon_{n\mathbf{k}})$ "// &
                          "using the Gaussian weight function "// &
                          "$g(x) = \exp(x^2/\alpha^2)/(\sqrt{2\pi}\alpha)$, $\alpha$ is the broadening "// &
                          "from the &DOS section, and the k-point weight "// &
                          "$w_\mathbf{k}$. The k-mesh is taken from the &DOS section.", &
                          n_keywords=2, repeats=.FALSE.)

      NULLIFY (keyword)
      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Activates the local VBM CBM gap calculation.", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="INTEGRATION", &
                          description="Defines whether the LDOS is integrated along a "// &
                          "coordinate. As an example, for INTEGRATION Z, the LDOS "// &
                          "$\rho(x,y,E) = \int dz\, \rho(x,y,z,E)$ is computed.", &
                          usage="INTEGRATION Z", &
                          enum_c_vals=s2a("X", "Y", "Z", "NONE"), &
                          enum_i_vals=(/int_ldos_x, int_ldos_y, int_ldos_z, int_ldos_none/), &
                          enum_desc=s2a("Integrate over x coordinate (not yet implemented).", &
                                        "Integrate over y coordinate (not yet implemented).", &
                                        "Integrate over z coordinate.", &
                                        "No integration, print cube file as function "// &
                                        "of x,y,z (not yet implemented)."), &
                          default_i_val=int_ldos_z)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create( &
         keyword, __LOCATION__, name="BIN_MESH", &
         description="Mesh of size n x m for binning the space coordinates x and y of "// &
         "the LDOS $\rho(x,y,E)$. If -1, no binning is performed and the "// &
         "fine x, y resolution of the electron density from SCF is used.", &
         usage="BIN_MESH  n m", &
         n_var=2, type_of_var=integer_t, default_i_vals=(/10, 10/))
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

   END SUBROUTINE create_ldos_section

! **************************************************************************************************
!> \brief creates an input section for a tip scan calculation
!> \param section section to create
!> \par History
!>    * 04.2021 created [JGH]
! **************************************************************************************************
   SUBROUTINE create_tipscan_section(section)
      TYPE(section_type), POINTER                        :: section

      TYPE(keyword_type), POINTER                        :: keyword

      CPASSERT(.NOT. ASSOCIATED(section))
      CALL section_create(section, __LOCATION__, name="TIP_SCAN", &
                          description="Parameters needed to set up a Tip Scan. "// &
                          "Needs external definition of tip induced field.", &
                          n_keywords=1, n_subsections=1, repeats=.FALSE.)

      NULLIFY (keyword)

      CALL keyword_create(keyword, __LOCATION__, &
                          name="_SECTION_PARAMETERS_", &
                          description="Controls the activation of the Tip Scan procedure", &
                          default_l_val=.FALSE., &
                          lone_keyword_l_val=.TRUE.)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SCAN_DIRECTION", &
                          description="Defines scan direction and scan type(line, plane).", &
                          usage="SCAN_DIRECTION XY", &
                          enum_c_vals=s2a("X", "Y", "Z", "XY", "XZ", "YZ", "XYZ"), &
                          enum_i_vals=(/scan_x, scan_y, scan_z, scan_xy, scan_xz, scan_yz, scan_xyz/), &
                          default_i_val=scan_xy)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="REFERENCE_POINT", &
                          description="The reference point to define the absolute position of the scan. ", &
                          usage="REFERENCE_POINT 0.0 0.0 1.0", &
                          n_var=3, default_r_vals=(/0.0_dp, 0.0_dp, 0.0_dp/), type_of_var=real_t, &
                          unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SCAN_POINTS", &
                          description="Number of points calculated for each scan direction.", &
                          usage="SCAN_POINTS 20 20", &
                          n_var=-1, type_of_var=integer_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="SCAN_STEP", &
                          description="Step size for each scan direction.", &
                          usage="SCAN_STEP 0.01 0.01", &
                          n_var=-1, type_of_var=real_t, unit_str="angstrom")
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

      CALL keyword_create(keyword, __LOCATION__, name="TIP_FILENAME", &
                          description="Filename of tip potential defined in cube file format.", &
                          usage="TIP_FILENAME <filename>", &
                          type_of_var=lchar_t)
      CALL section_add_keyword(section, keyword)
      CALL keyword_release(keyword)

   END SUBROUTINE create_tipscan_section

END MODULE input_cp2k_properties_dft
